1. Field of the Invention
This invention relates to novel 1-hydroxyvitamin D derivatives.
More particularly, it is concerned with esters of 1-hydroxyvitamin D with vitamin A acid.
The 1-hydroxyvitamin D derivatives are useful as an agent for preventing or treating osteoporosis, cutaneous ulcers and tumors.
2. Description of the Prior Art
There have been widely used active vitamin D having a hydroxyl group at the 1-position of the vitamin D as an agent for treating osteoporosis. Recently, the vitamin D derivatives have been found to have inducing activities on the differentiation of cells and tried to apply to the treatment of psoriasis and tumors.
On the other hand, vitamin A acid is biochemically synthesized from vitamin A and guessed to be an active intermediate at the expression of vitamin A effects. It is clarified that the functions of vitamin A such as growth stimulation, protein metabolism and stabilization of cuticula cell tissues are achieved via vitamin A acid. Considering those activities of vitamin A acid, there has been an idea to get useful compounds by esterification of such vitamin A acid with alcohols having physiological activities. For example, Japanese patent unexamined publication Nos. 469/1973 and 92967/1979 disclose esters of vitamin A acid with .alpha.-tocopherol (vitamin E). However, none of esters of vitamin A acid with vitamin D is known.